Blade-type drill bit



Oct. 20, 1964 Filed 00b. 8, 1962 Era- 1 L. W. SHORT BLADE-TYPE DRILL BIT2 Sheets-Sheet 1 INVENTOR.

ATTORNEYS Oct. 20, 1964 L. w. SHORT BLADE-TYPE DRILL BIT 2 Sheets-Sheet2 Filed Oct. 8, 1962 ATTORNEYS United States Patent 3,153,458 BLADE-TYPEDRILL BET Lot William Short, Dallas, Tex assignor to Drilling & Service,Inc, Detroit, Mich, a corporation of Delaware Filed (let. 8, i962, Ser.No. 228,998 9 Claims. (til. 175-329) This invention relates to ablade-type drill bit and more particularly to a drill bit using hard,abrading elements, such as diamonds, largely confined to and arrangedalong blade-like projecting ribs to form the cutting edges of the bit.Other portions of the working surface of the bit are provided that arefree of abrading elements and that, in general, conform in contour tosuch ribs but are radially inwardly olfset from said cutting edges toprovide bumper or abutment portions that by contact with the earthformation during the drilling operation determine the amount of bitetaken'by such cutting edges during rotation of the bit.

In accordance with my present invention, the working face of the bit isprovided with a plurality of Water grooves that extend from near the midportion of the lower working surface of the bit radially outwardly andupwardly, and the diamond-embedded cutting edges are formed alongcorresponding edges or" each of several such water grooves, such edgesbeing herein termed the leading edges. The other edges of the respectivewater grooves, which edges are herein termed the trailing edges, areleft free of abrading particles and constitute the bumper or abutmentportions previously referred to. The bumper portions, in addition tocontrolling the bite of the cutting edges, function to direct thedrilling fluid along the cutting edges and, in combination with properlydesigned and arranged water courses, serve to insure high velocity ofthe drilling fluid and thereby increase the efliciency of the fluid inbottom scavenging and in the removal of earth. formation cuttings.

A blade-type drill bit embodying the features of construction andfunctioning in the manner similar to that just described is disclosedand claimed in my pending application for patent Serial No. 195,595,filed May 17, 1962. The drill bit of my present invention, however,distinguishes from the drill bit construction therein disclosed in thatthe lower working end of my present drill bit is generally sperical, orball-shaped, in contour. This insures better load distribution over theworking face of the bit during the drilling operation. As is well known,the average drill collar string used in rotary drilling is a longslender string that will buckle and become unstable under the effects ofcolumnar loading, such that at any given instant during a revolution ofthe bit, a small area on one side of the working face of the bit isobliged to carry most of the load. This is particularly true if the axisof the bottom drill, revolves about the axis of the hole being drilled.Where, however, the lower working face of the drill bit is substantiallysperical, or ballshaped, such localized overloading of an area of theWorking surface is much less likely to occur under sim larcircumstances.

It is therefore an important object of this invention to provide a drillbit of a blade-type construction that possesses novel operationaladvantages in the drilling of bore holes in various types of earthformations.

It is a further important object of this invention to provide a drillbit of improved construction in which there is a more efl'icientutilization in operation of high velocity streams of drilling'fiuid bothwith respect to the cooling of the abrading elements in the cuttingedges of the bit and also in the removal of the earth formation cuttingsformed during the drilling operation.

It is a further object of this invention to provide, in a drill bit, alower portion of the bit that is generally sperical, or ball-shaped, incontour, and that is provided with a plurality of water groovesextending outwardly and upwardly from near the mid-point of the lowersurface of the bit, and that is further provided along leading edges ofa plurality of such water grooves with cutting edges substantiallycontinuous in extent with such grooves, and along the other, or trailingedges of the same grooves is provided with non-cutting surfaces that areslightly oilset axially upwardly and/ or inwardly to function as bumperor abutment portions, the trailing edges in cooperation with the leadingedges defining the bite taken by the cutting edges of the bit duringrevolution thereof.

Other objects, features and advantages of this invention will becomeapparent to one skilled in the art from the following description of theembodiments of the invention illustrated in the accompanying drawings,in which:

FIGURE 1 is an elevational view of a drill bit embodying the features ofmy invention;

FIGURE 2 is a bottom plan view of the bit, rotated slightly from itsposition in FIGURE 1;

FIGURE 3 is a sectional view taken substantially along the broken lineIII-J11 of FIGURE 2;

FIGURE 4 is an enlarged fragmentary sectional view taken along the lineIV--IV of FIGURE 1; and

FIGURE 5 is an enlarged fragmentary sectional View taken along the lineVV of FlGURE 2.

As shown on the drawings:

The drill bit illustrated in the drawings is one adapted to be attachedto the lower end of a drill stem in the drilling of oil wells and thelike, wherein the drill stern (not shown) is rotated by a rotmy table(not shown) and wherein the drilling fluid, such as any of thosecommonly used for the purpose, is circulated down through the drill stemand discharged through the lower Working end of the drill bit. Thedrilling fluid serves the purpose of cooling the abrading elements ofthe bit and of carrying away from the bottom of the bored hole theparticles of earth formation generated by the abrading action of thedrill bit or otherwise present in the bottom of the hole. As is Wellunderstood, the drilling fluid is usually a water suspension of a clay,or mud, and is pumped down through the drill stem to the drill bit underconsiderable pressure. As will be explained hereinafter in greaterdetail, the particular construction and arrangement of the fluiddischarge bores and water grooves in the bit of my invention, incombination with the configuration of the working face of the bit andthe constriction of the Water grooves toward the periphery of suchWorking face, results in a higher velocity flow of drilling fluid overand across the abrading elements during their cutting action than hasheretofore been usually the case.

With more specific reference to the drawings, the reference numeral ltlindicates generally a drill bit of my invention, provided at its upperend with a cylindrical shank 11 having a bore 12 therethrough. Whilebits of the type here under consideration may be either internally orexternally threaded for attachment to the drill stem, the presentembodiment is here illustrated as internally threaded, and the externalsurface of the shank 11 is provided with wrench-engaging depressions 13to facilitate the threading operation. The shank ii is thus hollow andis provided with internal threads 14 for attachment to the drill stem.

The body of the bit, indicated at 15, is carried at the lower end of theshank 11, sometimes integrally therewith and sometimes rigidly attachedthereto in any suitable manner. Said bit body 15, so far as its generalcontour is concerned, is substantially spherical both in bottom planview and in elevation, although the centers of curvature for the twosets of surfaces involved need not be exactly coincident along the axisof shank and bit body. In bottom plan view, as in FIGURE 2, thecircularcontour of the substantially spherical lower portion of the bitis indicated by the reference numeral 16 and for the generally sphericallower portion of the body of the bit shown in elevation in FIGURE 1, bythe reference numeral 17. The upper portion of the bit body 15 has anouter cylindrical surface 18 of slightly larger diameter than either thetransverse diameter of the lower portion of the bit or the diameter ofthe shank 11, with a sloping surface or shoulder 19 extending betweenthe cylindrical portion 18 of the bit and the lower cylindrical portionof the shank 11.

As best shown in FIGURE 2, the drill bit body 15 is provided with aplurality of water courses, or grooves, four in all in the embodimentthere illustrated. Depending upon the size of the bit, more or fewerwater courses might be employed, but four water courses are preferredfor a bit having an outside diameter of about 9 or 10 inches. The fourwater courses illustrated are designated, respectively by the referencenumerals 20, 21, 22 and 23, the bottom surfaces of which are constitutedby portions of the generally spherical surfaces that includes the circleshown in plan view (FIGURE 2) and indicated by the reference numeral 15.Said waterways, or grooves, 20, 21, 22 and 23 are relatively deep andextend outwardly from near the midpoint of the lower surface of the bitand upwardly along the perimeter past the enlarged cylindrical portion18 at the upper portion of the bit body 15. Each of said grooves is ofsubstantial depth and the depths of the several grooves aresubstantially the same, but the cross sectional areas of the respectivegrooves vary one from another and also vary along their respectivelengths. In the case of three of the water grooves, which will be termedthe main water grooves, identified by the reference numerals 21D, 21 and22, the leading edges 24, 25 and 26 thereof extend substantiallyradially outwardly, as viewed in FIGURE 2, and extend upwardly, acrossthe height of the enlarged cylindrical surface 13, to the slopingsurface 19, as shown in the case of the water groove 20 in FIG- URE 3.

Each of said leading edges 24, 25 and 26 being generally of similarconstruction and arrangement, it should sulfice to describe only theleading edge 25, since that edge is more fully described in thedrawings. Said edge 25 (FIG- URE is defined by the generally plane wall27 of a sintered tungsten carbide insert, or blade B, forming a wall ofthe groove 21, and an external surface 28 of said blade B forming acontinuation of the external generally spherical working face of the bitbody 15. The blades B, three in number, are separately formed ofsintered tungsten carbide With diamonds embedded in the edges that areto form the cutting edges 24, 25 and 26, and these blades are theninserted in the mold in which the bit is formed. In this Way diamonds D,or other abrading particles, are set substantially continuously alongthe entire arcuate extent of the edges of the blades B to convert saidedges into cutting edges, or ribs. As shown in FIGURES 1 and 3, the edge25, extends upwardly through the annular cylindrical enlargement 18 andthe diamonds D are embedded continuously therealong, preferably in asingle row, or in not more than two or three rows, except along theannular portion 18 where the diamonds are set over a widened area toprovide lateral reaming surfaces L.

The portion of the external working surface of the bit body 15 that lieson the opposite side of the water groove 21 from the surface 28provides-what is herein termed a bumper or an abutment surface 30. Theedge of the bumper surface 31 at the groove 21 constitutes the trailingedge 31 of said bumper surface. Said bumper portion 36 extends upwardlyuntil it merges with the generally cylindrical surface 18. The trailingedge 31 is offset radially and/or axially-inwardly of the leading edge25 formed along the insert or blade B throughout substantially their .5-full extents. The amount of said offset is illustrated in FIGURE 5 bythe reference letter D and is substantially the same throughout theextents of the leading edge 25 and the trailing edge 31. It is thisamount of offset that determines the bite taken by the leading edge 25of the rib 29, as will be more fully explained hereinafter.

With further reference to the water groove 21, it will be noted thatsaid groove is of varying width along the lower generally sphericalportion of the bit body, being wider at approximately the mid portionthereof, as indicated. by the letter W than it is either at its innerend I or its outer end 0. A water bore 32 opens into the wider portion Wof said water groove 21. Said bore 32 extends through the body 15 of thebit from a counterbore 12a (FIGURE 3) forming a continuation of the bore12 of the shank 11. Thus, drilling fluid can be pumped down through thedrill string and the hollow shank into the bore 32 for discharge intothe water groove 25. Similar water bores 33 and 34 are provided fordischarging drilling fluid into the water grooves 22 and 20,respectively. All of said bores 32, 33 and 34 are restricted at theirdischarge ends to provide jets I. Said water grooves 21 and 22, like thewater groove 21, are wider near the mid portions of their lower extentsand are restricted as they continue upwardly along the lateral face ofthe bit body.

In the case of the protuding rib or cutting edge 25, said edge extendsinwardly beyond the center of the lower surface of the bit asrepresented by the reference letter C (FIGURE 2) lying on the true axisof the bit body 15. The extension of the cutting edge 25 beyond thecenter point C insures an effective cutting action across the axis ofthe hole being drilled and eliminates the existence of any dead spotsuch as would occur if all of the cutting edges terminated short of thecenter point C or passed directly through said center point. By virtueof its extension beyond the center point C and slightly offsettherefrom, the cutting edge 25 exerts a cutting action across thecorresponding center point of the bottom of the hole being bored. Thecorresponding cutting edges 24 and 26, respectively, are shorter thanthe cutting edge 25 and terminate at their inner ends well short of thetrue center C. However, like the cutting edge 25, the edges 24 and 26are offset axially and/or radially outwardly from the correspondingtrailing edges 37 and 33 of the water grooves 20 and 22, respectively,by the same amount of offset as that represented by D between thecutting edge 25 and the trailing edge 31 (FIGURE 5).

In the illustration of my invention there are, therefore, three mainwater grooves, namely water grooves 20, 21 and 22, and the same numberof corresponding sets of cutting edges 24, 25 and 26 paired withcorresponding trailing edges 37, 31 and 38 of bumper portions 40, 30 and42. These bumper portions are free of abrading particles. The bumperportions 30 and 42 are continuous portions of the external workingsurfaces on which are formed the cutting edges 24 and 25, respectively,while the bumper portion 40 is a fragmentary portion of the externalsurface that is isolated from the other external surface portions of thelower part of the bit by the water grooves 20 and 23. The Water groove23 also differs from the other water grooves in that it has a relativelyshort, narrow inner portion, or throat T, from which it flares laterallyoutwardly over the generally spherical surface S of the bit body 15 andcontinues upwardly along the lateral more or less cylindrical extensionCE thereof (FIG. 1).

By virtue of the construction thus far described, there are three areasthat might be termed jet areas in each of the three main waterways 21),21 and 22. The waterway 23 is without any jet area, since, unlike theother waterways, there is no bore leading directly into the waterway 23.The drilling fluid discharged through the bores 32, 33 and 34 isdirected mainly outwardly and upwardly along the respective Watercourses 21, 22 and 20 into the annulus between the outside diameter ofthe shank 11 and the drill hole wall. Some of the drilling fluid flowsinwardly from the respective bores 32, 33 and 34 toward the lowercentral portion of the bit and outwardly through the throat T into thelow pressure waterway 23 and thus outwardly and upwardly between thedrill bit shank and the wall of the hole being drilled.

In operation the drilling action of the bitris substantially as follows:when sufficient weight, or load, is applied to the bit, the cuttingedges provided by the diamondset ribs 24, 25 and 26 bite into the earthforma-. tion to the depth, approximately that represented by thereference numeral D, permitted by the relatively large cross-sectionalareas of the'bumper or abutment portions 40, 30 and 42. The latter comeinto contact with the earth formation at the bottom of the hole beingdrilled and prevent further penetration of the cutting edges into theformation. As the bit is rotated 120 there will be a penetration orremoval of formation corresponding to the extent of the controlled bite.The formation so out, or abraded, is discharged quickly through thewaterways 20, 21, 22 and 23.

The fluid flow pattern, with the blades sunk into the formation and withthe bumper areas in contact with the bottom of the hole is as follows:the fluid is delivered through the three jet nozzles I represented bythe discharge ends of the bores 32, 33 and 34 into the respective jetareas of the water grooves 21, 22 and 20. In operation, the jet velocityof the drilling fluid so discharged through the discharge ends of saidbores 32, 33 and 34 is approximately 500 feet per second. The jetstreams are deflected in directions initially determined by the walls ofthe waterways 20, 21 and 22 over the bottom surfaces of said waterwaysand upwardly along the lateral surfaces thereof and thence into theannulus between the drill shank and the wall of the hole. In usualoperation the fluid velocity of the drilling fluid is never less thanabout 200 feet per second, the minimum velocity being along the bottomof the hole inwardly of the discharge openings of the bores 32, 33 and34.

As previously pointed out, owing to the ball-shaped contour of the lowerportion of the bit body 15, the load on the drill string is more equallydistributed over the working surface of the bit than where bits are usedhaving non-spherical working surfaces. By comparison with other contoursof drill bits it has been found that the load distribution is best whena ball-shaped bit contour is used.

I claim as my invention:

1. A drill bit comprising: a bit body having at its upper end an axialrecess and at its lower end a working face, said working face includingan upper generally cylindrical annular reaming portion and a generallyspherical lower surface portion of lesser transverse diameter than saidannular portion, said working face being formed with a plurality ofwater grooves extending from near the midpoint of said lower surfaceportion to the periphery thereof and upwardly through said annularportion, the

working face along corresponding leading edges of respective groovesprojecting outwardly beyond the trailing edges of said respectivegrooves for substantially the full extents of said grooves over saidlower surface portion to provide ribs, abrasive particles embedded inand along said ribs to constitutecutting edges, said trailing edges 7cutting edges extends along an are that terminates beyond and is.slightly offset from the projected axis of said spherical portion toeffect a cutting action across said projected axis.

3. Adrill bit comprising: a hollow cylindrical shank, a bit body at thelower end of said shank having an axial recess forming a continuation ofthe hollow in said shank, said bit body having an upper annular workingface portion of larger diameter than said shank and a lower generallyspherical working face portion of lesser transverse diameter than saidannular portion, there being a plurality of relatively deep watergrooves extending from near the midpoint of said lower spherical portionoutwardly thereof and upwardly through said annular portion, saidgrooves being in open flow communication near said midpoint to formcontinuous water flow passages thereacross, said working face portionsalong correspondingly leading edges of some of said grooves projectingoutwardly of the respective trailing edges of said grooves asubstantially uniform distance for substantially the full extents ofsaid grooves over said lower generally spherical working face portion toprovide ribs continuous therealong, abrasive particles embedded in andalong said ribs to form cutting edges, said trailing edges and adjacentworking face portions being free of abrasive particles and functioningduring the drilling operation as abutments to determine the depth of thebite taken by said cutting edges, there being bores extending from saidaxial recess through said bit body into some of said grooves todischarge drilling fluid thereinto for passage along said groves andupwardly past said shank during the drilling of a hole in an earthformation.

4. A drill bit as defined in claim 3 wherein there are three watergrooves each provided with a bore for the discharge of drilling fluidthereinto, and there is a fourth water groove directly opposite one ofsaid three water grooves but having no bore provided for dischargedirectly thereinto, said fourth groove discharging outwardly over anenlarged upwardly flared area provided by a segmental spherical surfacelying inwardly of said generally spherical working face portion.

5. A drill bit as defined in claim 3, wherein each water groove having abore for discharging drilling fluid thereinto is abruptly constricted incross section outwardly of the opening therein of such bore.

6. A drill bit as defined in claim 3, wherein each of said bores issmoothly and abruptly restricted at its lower end to provide a jetdischarge opening into its corresponding water groove.

7. A drill bit as defined in claim 4, wherein each water groove isrestricted at its inner lower end and those water grooves provided withbores discharging directly thereinto are also restricted incross-sectional area outwardly toward the lateral periphery of said bit.

8. A drill bit as defined in claim 3, wherein one of said cutting edgesextends inwardly past and offset from the true axis of said bit.

9. A drill bit as defined in claim 3, wherein each of said cutting edgesis provided by a relatively narrow, elongated, sintered tungsten carbideinsert having diamonds set continuously along an edge thereof to providea cutting edge.

References Cited in the file of this patent UNITED STATES PATENTS2,009,742 Mitchell July 30, 1935 2,186,725 Hughes Jan. 9, 1940 2,371,489Williams Mar. 13, 1945 2,371,490 Williams Mar. 13, 1945 2,582,231Catallo Jan. 15, 1952' 2,855,181 Olsen Oct. 7, 1958 2,998,088 PenningtonAug. 29, 1961 3,095,053 Pistole et al. June 25, 1963 FOREIGN PATENTS1,249,346 Fnance Nov. 21, 1960 Attesting Officer NITED STATES PATENToFFic Pa tent No. 3,153,458 Octo ber 20, 1964 Lot William Short,

It is hereby certified that error appears the above numbered patentrequiring correction and thatthesaid Letters Patent should read'ascorrected below. Y

' In the grant, lines 2 and 3, for "assignor .to Drilling 8: Service,Inc. of Detroit, Michigan, a corporation of' Delaware," read assignor toDrilling 8z Service, Inc. a wholly-owned subsidiary of WheelTrueing,Tool' Company, of Detroit, Michigan a corporation of Delaware line 12,a for "Drilling 81 Service, Inc. its successors" read Drilling 8:Service, Inc. a wh oll.y-own.ed. subsidiary ofwheel Trueing ToolCompany, its successors -,I;' inthe heading to the printedspecification, lines 3 and 41, for "assignor to Drilling 81 Service,Inc. Detroit, Mich, 4a corp-oration of. Delaware" read assignor toDrilling 81 Service, Inc a wholly owned sudsidiary of Wheel Trueing.Tool Company, Detroit, Mich. a corporation of Delaware,

Signed and sealed this 20th day of April 1965.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER

1. A DRILL BIT COMPRISING: A BIT BODY HAVING AT ITS UPPER END AN AXIALRECESS AND AT ITS LOWER END A WORKING FACE, SAID WORKING FACE INCLUDINGAN UPPER GENERALLY CYLINDRICAL ANNULAR REAMING PORTION AND A GENERALLYSPHERICAL LOWER SURFACE PORTION OF LESSER TRANSVERSE DIAMETER THAN SAIDANNULAR PORTION, SAID WORKING FACE BEING FORMED WITH A PLURALITY OFWATER GROOVES EXTENDING FROM NEAR THE MIDPOINT OF SAID LOWER SURFACEPORTION TO THE PERIPHERY THEREOF AND UPWARDLY THROUGH SAID ANNULARPORTION, THE WORKING FACE ALONG CORRESPONDING LEADING EDGES OFRESPECTIVE GROOVES PROJECTING OUTWARDLY BEYOND THE TRAILING EDGES OFSAID RESPECTIVE GROOVES FOR SUBSTANTIALLY THE FULL EXTENTS OF SAIDGROOVES OVER SAID LOWER SURFACE PORTION TO PROVIDE RIBS, ABRASIVEPARTICLES EMBEDDED IN AND ALONG SAID RIBS TO CONSTITUTE CUTTING EDGES,SAID TRAILING EDGES TOGETHER WITH SUBSTANTIALLY FLAT SURFACES EXTENDINGTHEREFROM BEING FREE OF ABRASIVE PARTICLES AND FUNCTIONING DURING THEDRILLING OPERATION AS BUMPERS TO DETERMINE THE EXTENT OF THE BITE TAKENBY SAID CUTTING EDGES THERE BEING BORES EXTENDING FROM SAID AXIAL RECESSTO SAID GROOVES TO DISCHARGE DRILLING FLUID THEREINTO.